1. Field of the Invention
The present invention relates to a method and nodes for handling Multicast messages.
2. Description of the Related Art
Recent years have seen the explosion of Internet Protocol (IP) networks. Initially developed to allow universities and researchers to communicate and cooperate in research projects, it has grown into networks offered at a mass-market level. Nowadays, it is normal for households to have a connection to an IP network to surf the world-wide-web, play interactive games, carry Voice over IP, download documents and softwares, make electronic business transactions, etc.
Reference is now made to FIG. 1, which represents a prior art example of an IP network 100. Typically, an IP network is composed of an access domain 115, network service provider domains 140 and application service provider domains 150. The access domain 115 includes Access Nodes (AN) 120 and an access network 130, such as an IP network. The ANs 120 are network providers, which can offer access to the IP network 130 to user domains 110. The user domains 110 include for example User Devices (UDs) (such as computers, mobile phones, personal digital assistants, etc.), Local Area Networks (LANs) and Wireless-LANs (W-LANs). The user domains communicate with the ANs over various possible technologies. Amongst those technologies can be found dial-up connections and Asymmetric Distribution Subscriber Line connections over telephone lines, cable modems connecting over television cable networks, or wireless communications. The access network 130 is composed of a group of independent routers, which task is to route incoming data traffic based on a destination address embedded therein. As for the network service provider domains 140, they may correspond for example to Voice over IP services, while the application service provider domains 150 may correspond to electronic banking and electronic business transactions.
Though FIG. 1 depicts three user domains, two Access Nodes, two service provider domains and two application service domains, IP networks 100 typically include several thousands of user domains, tenths of Access Nodes, hundreds of service provider domains and application service provider domains. As to the access network 130, it is common to encounter networks including hundreds of routers. It is thus understood that FIG. 1 depicts a highly simplified IP network 100 for clarity purposes.
The initial principle at the basis of IP networks is to rely on switches and routers, which perform as few and as little operations as possible before routing incoming data traffic towards their final destination. For doing so, different kinds of messages are available: Unicast messages, Multicast messages and Broadcast messages. For each of those three types of messages, ranges of addresses are allocated for each type of messages. Unicast messages are used to exchange messages between one sender and one recipient. Multicast messages allow one sender to reach multiple recipients. As to broadcast messages, they are used to reach all switches part of a segment of the IP network.
More particularly, multicast messages are generated by Service Provider Domains. Since Service Provider Domains control their IP address space, they may use overlapping addresses in the multicast domain. Multicast messages from different Service Provider Domains using the same Multicast address will be merged into a single multi-service provider stream. This single multi-service provider stream will then be forwarded to all the access nodes on which a user domain has previously joined the multicast group, independent of the Service Provider Domain. Such a management of multicast may result in a flooding of the access nodes and user devices with unnecessary traffic.
There is currently no known solution to the problems associated with the explosion of the number of user devices and of service providers offering services on IP networks. Furthermore, no long-term solution has been identified to allow a tangible solution to the potential nuisance caused by Multicast messages over large IP networks servicing thousands of User Domains.
Accordingly, it should be readily appreciated that in order to overcome the deficiencies and shortcomings of the existing solutions, it would be advantageous to have a method and nodes for efficiently handling multicast messages, without unnecessarily overloading the network. The present invention provides such a method and nodes.